“Battery capacity” is a measure (typically in ampere hours) of the charge stored by the battery, and is determined by the mass of active material contained in the battery. The battery capacity represents the maximum amount of energy that can be extracted from the battery under certain specified conditions. The available capacity of the battery may be referred to as the relative state of charge (RSOC). Typically expressed as a percentage, RSOC is the ratio of the remaining capacity to the full charge capacity (FCC).
Temperature affects the full charge capacity of the battery. Referring to FIG. 4, in general, as the temperature decreases, the capacity decreases, and vice versa. Since the RSOC is computed based on the capacity value, the RSCO also increases or decreases according to temperature. The effect of temperature on the battery capacity results in inaccurate reporting of the RSOC.